Piston type compressor



Sept. 24, 1957 Filed April 23, 1951 a. w. FOSTER 2,807,136

PISTON TYPE COMPRESSOR 4 Sheets-Sheet 1 Fig.1. /3 4 43 /4 Y5 g. g /6 /Z= 2 "I 4 o o /Z4 23 i 62 2 2 2 3 2 a 2 E L 5936 L 26 so" "24- 2- 4 z/z 56 Q 56 28 r n G2 4 60 E INVENTOR BERRY W- FOSTER A T TOR/V5 Y Sept. 24, 1957 a. w. FOSTER 2,807,136

PISTON TYPE COMPRESSOR 4 Sheets-Sheet 3 Filed April 23, 1951 Ill 9 5.

0 $0 61? MIMI/ [Ala/0 polo 3 K60171 161 104? INVEN TOR.

6- BERRY w. FOSTER ATTORNEY Sept. 24, 1957 5, w, os'r 2,807,136

PISTON TYPE COMPRESSOR Filed April 23, 1951 4 Shasta-Shut 4 Mayo/0) 5011111010 INVENTOI? BERRY W. FOSTER wwa A T TORNE' Y United States Patent 2,807,136 PISTON TYPE COMPRESSOR Berry W. Foster, Inglewood, Calif. Application April 23, 1951, Serial No. 222,368 5 Claims. (Cl. 60-35.6)

This invention relates to an improved compressor of the piston type and to a method of operating compressors and associated mechanisms.

A feature of the invention is the division of the compressed gas into two isolated portions. The internal power that runs the compressor is obtained by burning fuel in one of these two portions. The other portion represents the output of the compressor and the compressed gas therein may be stored, expanded, or be fueled and exploded according to the way the compressor is being used.

For example, my novel piston compressor may be part of a jet engine. In this case fuel is burned in both of the isolated portions of the compressed gas. The energy in the one part operates the compressor, while the energy in the other part propels the airplane or other vehicle.

Heretofore, all the heated gases were expanded together, usually in one chamber, whether the engine was of the piston type or of the turbine type. In the present invention only a portion of the total amount of fuel is burned in the compressor cylinder or in a chamber that is in commuincation with it at the time of burning. The rest of the fuel is burned in an isolated second portion of compressed gas outside the compressor cylinder. The result is an important simplification of engine operation and greater efficiency in the use of its power.

Suppose that the volume of the compressed gas that is isolated outside the compressor cylinder on each compressor stroke is a, and that b is the volume of the compressed gas isolated in the cylinder chamber at the moment of isolation and the addition of energy. Then, if the unit masses of the compressed gas in a and b are m and m, respectively, the total mass M of the compressed gas will be: M :am,+bm,. The energy in the mass bm, should be as near as possible to the exact amount which, when energy is added, will compress a second mass M to the same compression ratio, by driving the piston back across the cylinder at the opposite end of the cylinder, or by driving a second piston in a second cylinder by transmitting the power from the first piston through a rod and crank. The output energy am is available as external power, and the operating efiiciency of the engine is at its peak when am is large in proportion to bm,.

The invention may also be used to supply a storage tank with compressed gas. Again, at each stroke (or each alternate stroke) a portion of the compressed gas is isolated, energy is added, and the resultant expansion of this portion of the gas drives the compressor piston, while the rest of the compressed gas is conducted into the storage tank. The energy in the gas that drives the piston is sufficient to move it toward the other end of the cylinder and compress a like amount there.

My novel compressor unit may employ a free piston instead of a piston having a connecting rod and crankshaft, but the invention dilfers from other firee-piston engines in several particulars, including the following: (1)

separated from the external-power The compressor air is air before heat is added, so that only a fraction of the ice total amount compressed is expanded in the compressor engine. (2) The external-power air performs no work on the piston. (3) The compressor air does all the work on the piston. (4) The piston itself does no external work, although the heated gases which are expanded in the compressor engine may do some external work if that is desirable. Usually, however, this is kept to a minimum.

In all modifications of the invention, the compressor piston preferably does no external work and supplies none of the external power, acting only: (1) to compress the gases, and (2) in some instances to precompress the intake air to a small pressure ratio for scavenging the burnt gases. All or practically all the external power is supplied by the separate portion of the air which is isolated from the compressor cylinder.

Other objects and advantages of the invention can be better understood from the following description of several embodiments thereof illustrated in the accompanying drawings. However, it is to be understood that the drawings and descriptions are illustrative only and are not definitive of the invention, the scope of which is stated in the appended claims.

In the drawings:

Fig. l is a diagrammatic view of one form of a jet-type engine employing a compressor embodying the principles of this invention. The engine shown here has two cylinders whose pistons are joined on a common crank shaft. This view shows the engine being started with the piston at the left approaching the head end of its cylinder, while the other piston is approaching the crank end of its cylinder.

Fig. 2 is a view similar to Fig. l, with the pistons now moving in the opposite directions, and with the valves and other parts in their proper position for this stage of the cycle.

Fig. 3 is a view similar to Fig. 2, with the pistons further advanced on this stroke, and with the valves and other parts in the position which they then assume.

Fig. 4 is a view similar to Fig. 1, with the pistons in positions approximately the extreme opposites from the Fig. 1 positions.

Fig. 5 is a diagrammatic view of a modified form of engine embodying the invention and employing a single free piston. The engine is shown at the beginning of operation, with the piston moving toward the left.

Fig. 6 is a view similar to Fig. 5, showing the piston at the end of its left hand stroke.

Fig. 7 is a view similar to Fig. 5, showing the piston moving toward the right from its extreme left-hand position.

EXAMPLE 1 (FIGS. 1 TO 4) A two cylinder engine with crank connection and with precompressors I shall first show an engine that has a two-stroke, singleacting, compressed-gas generator, with a precompressor. Figs. 1 to 4 illustrate diagrammatically a preferred form of this type of embodiment of the invention, in which there are two compressor cylinders and two pistons linked together by a common crank shaft. There may he more cylinders and pistons, if desired.

Two pistons 1 and 2 reciprocate in their respective cylinders 3 and 4. Connecting rods 5 and 6 may join the pistons 1 and 2 to a common crankshaft 7. The crankshaft 7 is connected to or made integral with a pair of camshafts 9 and 10. The camshafts 9 and 10 control the engine valves, injectors, and other moving parts. by means of the several cams mounted thereon. Although two camshafts 9 and 10 have been shown for purposes of illustration, one camshaft may be sufiicient, or there may be more than two camshafts.

Adjacent the head ends 11 and 12 of the cylinders 3 and 4 there may be jet explosion (output) chambers 13 and 14. The chamber 13 may be connected to the cylinder 3 by a port 15. The port 15 may be closed by a valve 17 so as to isolate the output chamber 13 from the cylinder 3. The valve 17 may be moved into and out of its closed position by the reciprocation of a rod 19, whose movement is controlled by a cam 21 secured to the camshaft 9.

The chamber 14 and cylinder 4 may similarly be connccted by a port 16, which is opened and closed by a valve 18. The valve 18 may be operated by the rod 20 and a cam 22 secured to the camshaft 10.

Each cylinder 3, 4 has fuel injector nozzles 23, 24 located in chambers 11a and 12a, adjacent to the heads 11 and 12, and controlled by the camshafts 9, 10, through cams 25, 26 and rods 27, 28 respectively. The nozzle 23 may inject fuel into its cylinder 3 at approximately the time when the piston 1 reaches the head end of its stroke and after the port 15 has been closed by the valve 17. Similarly, one half cycle later, the nozzle 24 may inject fuel into its cylinder 4, when the piston 2 reaches the head end of its stroke and after the port 16 has been closed by the Valve 18. The explosion may be similar to that in a diesel engine, in which no special igniting means are required, or spark plugs or other igniting apparatus may be used if desired. The power obtained from the explosions in the cylinders 3, 4 is preferably not used externally, at least not to any great degree, but is used to operate the compressor unit.

Similar fuel injectors 31, 32 may be operated in the explosion chambers 13, 14 by the camshafts 9 and 10 through respective cams 33, 34 and rods 35, 36. Each injector 31, 32 fires its respective explosion chambers 13, 14 after its associated valve 17, 18 has closed its port 15, 16.

When the gas in each chamber 13, 14 explodes, its explosion products may pass out through exhaust ports or nozzles 41, 42. Each exhaust port 41, 42 is closed during the compression stroke of its associated piston l, 2 by a valve 43, 44 which opens at or just after the firing time. The valves 43, 44 may be controlled by the camshafts 9, 10 by means of cams 45, 46, rods 47, 48, and cranks 49, 50.

The rush of exhaust gases out of the nozzles 41, 42 supplies the external power of the engine. This may be the jet which thrusts forward a direct type of jet propulsion power unit or it may turn a turbine whose shaft operates propellers, or any other desired type of unit may be used.

At the crank ends 51, 52 of the cylinders 2 and 4, there may be precompression chambers 53, 54 respectively. On the crank-to-head stroke of each piston l, 2, a check valve 55, 56 opens and lets atmospheric or super charged air into its through ports 57, 58. is compressed on the 1, flows around the when the piston 1 is This pre-compressed the head end of the The air in the chamber 53, which head-to-crank stroke of the piston piston 1 through ports 59 and 61 near the crank end 51 (ref. Fig. 4). air scavanges the burnt gases from cylinder, forces them out through the port 15, scavenges the burnt gases from the chamber 13, and forces all these burnt gases to exhaust through the port 41. Likewise, when the piston 2 is at its crank end 52, compressed air flows into chamber 12 through ports 60 and 62 (ref. Fig. 1), scavenges the burnt gases in the chambers 12, and 14, and exhausts it through the ports 16 and 42.

The operation of the device of Figs. 1 to discussed with reference to the different cycle illustrated in these drawings.

Referring first to Fig. l, a conventional starter (not shown) may rotate the crankshaft 7 and move the pistons 1 and 2 past the center of the cylinders 3 and 4 so that at least one of them draws in a. fresh charge of air. Here 4 will now be stages of the precompression chamber 53, 54

the piston 1 is arbitrarily shown moving to the head end 11 of the cylinder 3, and the piston 2 is shown moving toward the crank end of the cylinder 4. Air is being drawn from a supercharger (not shown) or from the atmosphere into the cylinder 3 through the port 57 on the crank-to-head stroke of the piston 1. The exhaust valve 44 is unseated from the exhaust port 42. The valve 43 is keeping the port 41 closed, and the valves 17, 18, and 55 are open. Since the engine has not yet been started, the valve 56 is also open, because there is no pressure above the cylinder 2 that would cause the valve 56 to close its port 58.

Referring now to Fig. 2, the piston 1 is in almost the same position as in Fig. l, but is moving toward the crank end 51 of the cylinder 3, and the piston 2 is moving toward the head end 12 of the cylinder 4. The power is still being supplied by the starter. The valve 17 has closed the port 15, and the exhaust valve 43 still holds the exhaust port 41 closed. The air intake port 57 has been closed by the valve 55, and the piston 1 is beginning to compress the fresh air in the pre-compressor 53 at the crank end 51 of the cylinder 3.

In the cylinder 4, the intake port 58 has been closed by the valve 56. The isolating valve 18 is open and the exhaust valve 44 is closed, so that the piston 2 is now compressing gas into both the chamber 12a and its associated jet explosion chamber 14.

In Fig. 3, the piston 1 has moved down toward the crank end 51 of its cylinder 3. The valve 55 has closed the air intake port 57, and air is being compressed in the precompression chamber. The isolating valve 17 remains closed, but the exhaust valve 43 has opened the exhaust port 41.

The piston 2 has moved beyond the port 62, and the air-intake valve 56 has opened the port 58. Fresh air is admitted from the atmosphere (or a supercharger) into the pre-compressor 54 through the port 60. The exhaust valve 44 remains closed, and the isolating valve 18 remains open, so that into the chamber 14 and into the head end of the cylinder 4.

As the piston 1 reaches the position shown in Fig. 4, it is near the end of its head-to-crank stroke. The precompressed air in the precomprcssor 53 passed around the piston 1 through the ports 59 and 61. It scavenges any stale gases from the chamber 11a, ejecting them through the port 15. It then scavenges all the stale gases from the chamber 13 and ejects them through the open exhaust port 41. Fresh air is in the upper end of the cylinder 3 and in the chamber 13, ready for the isolating the output chamber 14 from the cylinder 4. The valve 18 acts very quickly and within a small fraction of a second thereafter the injectors 24 and 32 force fuel into their two chambers 4 and 14, preferably simultaneously. The explosion of the gas in the chamber 14 acts to heat the compressed air therein and at this instant the valve 44 (shown closed in Fig. 4) open the port 42 so that the high energy explosion products rush out of the chamber 14 and pass out through the nozzle 42, to supply the external power.

At the same instant the heated gas in the chamber 12a acts to force the piston 2 toward the crank end 52 of the cylinder 4, where they were in Fig. l, the explosion providing sutficient power to compress a like mass of air in the chambers 11a and 13 of the cylinder 3 to the same compression ratio. This power is transmitted between the two pistons 1, 2 by the crankshaft 7. Preferably the crankshaft 7 transmits no external power, although the engine could be designed so that it would deliver crankshaft power. Preferably, all or substantially all of the external power comes through the exhaust nozzles 41, 42.

At the same time, the movement of the piston 2 precompresses air to a small compression ratio in the chamber 54. When the piston 2 again reaches the crank end 52 of its cylinder 4 (ref. Fig. 1), the precompressed air in the chamber 54 will flow through the ports 60 and 62 and scavenge the burnt gases through the ports 16 and 42, and a fresh charge of air will be introduced on the head end of the piston 2.

Meanwhile, the piston 1 is compressing air in the chambers 11a and 13, and when the piston 1 again moves to its Pig. 2 position, fuel is injected into the chambers 11a and 13 by the injectors 23 and 31, and is exploded a moment later.

The engine is now started, and it will continue to run until the fuel supply is cut oil.

From now on, whenever the piston 1 moves to the crank end 51 of its cylinder 3 (its Fig. 4 position) the valve 17 will open the port 15. The old air will be expelled through the ports 15 and 41 with a fresh charge of air from the precompressor chamber 51 that flows into the chamber 11a through the ports 59 and 61. During this time the power from the explosion in the chamber 11a is being used up internally and the power from the chamber 13 is being used externally. When the internal power from the explosion in the chamber is used up, the piston 2 has compressed its air into chambers 12a and 14 and the fuel is exploded there. The power from the explosion in the chamber 12a is transmitted by the crankshaft 7 to the piston 1. As the piston 1 moves up to the head end 11 of the cylinder 3 (its Fig. 1 position) it compresses air in the chambers 11a and 13.

The piston 2 acts similarly, one half cycle out of phase with the piston 1. The power of piston 1 is transmitted through its connecting rod 5 to the crankshaft 7, then to the rod 6 and the piston 2. Similarly, the power from the piston 2 is transmitted to the piston 1. Air is pnecompressed at the crank end of the stroke by one piston, while the other piston is compressing air at the head end of its stroke.

Whenever the piston 1 reaches the end of its crank-to head stroke (ref. Fig. l), the chamber 11a is isolated from the chamber 13, and the injectors 23 and 31 cause another set of explosions at this end of the cylinder 3, which move the piston to the crank end again and the nozzle supplies more external power. One half cycle later, the piston 2 will reach the end of its crank-to-head stroke with similar results.

The power supplied by the explosions in the chambers 11a and 12a is used solely to operate the compressor, its piston, crankshaft, and valves, and no other power is required for this purpose once the engine has been started. All the power generated in the chambers 13 and 14 may be used externally.

EXAMPLE 2 (FIGS. 5-7) with Microswitch or brush switch controls A free-piston engine A two-stroke double-acting compressed gas generator is illustrated by Figs. 5 to 7, which show a modified form of the invention having a free piston 100 and a set of electrical connections controlled by a pair of brush switches (or microswitches).

The free piston 100 reciprocates in a cylinder 101. When the piston 100 moves to the left, it compresses gases into the left-hand engine chamber 102 and into a left-hand jet explosion chamber 110. When the piston 100 moves to the right, it compresses gas in the righthand engine chamber 103 and a right-hand jet explosion chamber 120. The chambers 102, 103 may have respective electrically actuated fuel injectors 104, 105.

The explosion chambers 110, 120 may be joined to the chambers 102, 103 by ports 111, 121 which are opened and closed by electrically actuated valves 112,

122. Fuel may be injected by electrically actuated injectors 113, 123. The exploded or expanded compressed gas may be exhausted through ports 114, 124, which may be opened and closed by electrically actuated valves 115, 125. From the ports 114, 124 the gases may be exhausted through the jet nozzles 116, 126.

An electrically actuated exhaust valve 130 may open and close an exhaust port 131 on one side of the central portion of the cylinder 101, while a similar valve 132 may open and close an inlet valve 133 on the other side of the cylinder, to admit air from a supercharger 134. These valves may be controlled by respective solenoids 135, 136.

At one or both ends of the cylinder 101 there may be an auxiliary compressor or storage tank 137, that is used only to start the engine and does no work after the engine is started. The air from the tank 137 may be admitted to the cylinder by a valve 138 that opens and closes a port 139.

In the engine chamber 102 near the end of the stroke of the free piston 100, there may be a brush switch or microswitch 141. A second brush switch or microswitch 143 may be located at the opposite end of the cylinder. These switches 141 and 143 may control the valves through a system of direct-action relays and delayed-action relays.

When the piston contacts the brush switch 141, a relay 150 may be actuated. If this is the first stroke of the piston 100, the relay may then close the valve 138 against its port 139, and no further air will be drawn from the compressor 137 so long as the engine is running and until it is started up again. On every such stroke, the relay 150 may open the exhaust valve and intake valve 132, by actuating the solenoids and 136. The old air will be exhausted and a new charge of air supplied. When the piston 100 breaks contact with the switch 141, it will again act on the relay to energize the solenoids 135, 136 and close the valves 130, 132.

When the piston 100 makes contact with the switch 141, the relay 150 may also operate to close the valve 112, isolating the chambers 102 and 110. The relay 150 may simultaneously actuate the fuel injectors 104 and 113 to send charges of fuel into the chambers 102 and 110. The relay 150 also may actuate a time-delay relay 151, which is timed so that the valve 115 will be opened the instant the gases in the jet chamber 110 have been heated. At the end of that short interval of time, the relay 151 may actuate a solenoid 152, which, through a toggle mechanism 153, may actuate the exhaust valve 115. The valve 115 will then open the port 114 and permit the gas to pass out the nozzle 116.

At the same time, when the piston 100 contacts the switch 141, it also actuates circuits that open the valve 122 and close the valve 125.

A relay 155 at the opposite end of the engine, controlled by the switch 143, may perform in the same man ner as the relay 150, the wires generally being in crossed relation except for the operation of the solenoids 135, 136 controlling the exhaust valve 130 and intake valve 132. Contact of the piston 100 with the switch 143 will then energize the relay 155. in addition to actuating the exhaust and intake valves 130, 132, the relay 155 closes the valve 122, actuates the fuel injectors 105 and 123, opens the valve 112, closes the valve 115, and energizes a time-delay relay 156, that after a short delay opens the valve 125 by means of a solenoid 157 and toggle mechanism 158.

To start the engine shown in Figs. 5 to 7, compressed air may be forced into the engine chamber 103 through the port 139. Suppose that the air will then move the piston 100 to the left from its Fig. 5 position to its Fig. 6 position. The valve 112 will be open and the valve 115 will be closed, so that gas is being compressed into the chambers 102 and 110. Meanwhile, the valve 122 is closed, as are the valves 115, 125 is open.

When the piston 100 reaches its Fig. 6 position, it contacts the switch 141 which causes the relay 150 to close the valve 138, which remains closed until the engine again has to be started. The relay 150 also actuates a circuit to close the valve 112, inject fuel through the injectors 104, 113, and start the time-delay relay 151 operating. The relay 150 also causes the valves 122, 130, and 132 to open and causes the exhaust valve 125 to close. When the fuel in the chambers 102 and 110 explodes, the expansion of gases in the chamber 102 starts the piston 100 moving to the right, while the gases in the chamber 110 supply external power.

When the piston 100 moves to the right to the position shown in Fig. 7, the switch 141 is opened, and the valves 130 and 132 close. The piston 100 begins to compress gas into the engine chamber 103 and the explosion chamber 120, the valve 122 being open and the valve 125 being closed. The power generated in the chamber 102 is sulficient to compress the large mass of air into these two chambers, but it need do no external work. In the meantime, the time-delay relay 151 has opened the valve 115, so that the external power gas can flow from the chamber 110 through the port 114 and out the jet nozzle 116.

The first half cycle is then duplicated on the right hand side of the cylinder 101 in the second half cycle, and then the cycle is repeated.

Iclaim:

l. A jet-type of engine having means "for compressing the air used for the fuel ignition and including in combination a compressor cylinder; a piston reciprocatable therein adapted to compress air alternately toward each of the two ends of said cylinder; a jet combustion chamber adjacent each end of said cylinder and connected therewith by a separating port; valve means for closing said separating port as said piston approaches its end of said cylinder, so as to isolate the air compressed in said jet-combustion chamber from the air compressed in the end of said cylinder; means for substantially simultaneously injecting fuel into the compressed air in said jetcombustion chamber and into the compressed air in said cylinder; means for substantially simultaneously exploding the two said injections of fuel; at least one nozzle exhaust port leading from each said jet combustion chamber; nozzle valve means for closing said nozzle exhaust port while air is being compressed and ignited in said jet combustion chamber; and means for opening said nozzle exhaust port to permit the passage of expanded gases, said separating port remaining closed during the expansion and explosion process, the expanded gases from the jet-combustion chamber being used to supply external power while the expanded gases in the cylinder are used to drive the piston toward the other end of said cylinder, where a similar explosion takes place.

2. A jet-type of engine having means for compressing the air used for the fuel ignition and including in combination a compressor cylinder; a free piston reciprocatable therein adapted to compress air alternately toward each of the two ends of said cylinder; a jet combustion chamber adjacent each end of said cylinder and connected therewith by a port; valve means for closing said port as said piston approaches its end of said cylinder, so as to isolate the air compressed in said jet-combustion chamber from the air compressed in the end of said cylinder; means for substantially simultaneously injecting fuel into the compressed air in said jet-combustion chamber and into the compressed air in said cylinder; means for substantially simultaneously exploding the two said injections of fuel, the expanded gases from the jet-combustion chamber being used to supply external power while the expanded gases in the cylinder are used to drive the piston toward the other end of said cylinder, where a similar explosion takes place; and electric switch means actuated by the move- 130, and 132, and the valve ment of said free piston in said cylinder for actuating said valve means, said fuel injection means, and said explosion means.

3. A jet-type of engine having means for compressing the air used for the fuel ignition and including in combination a compressor cylinder; a free piston reciprocatable therein adapted to compress air alternately toward each of the two ends of said cylinder; a jet combustion chamber adjacent each end of said cylinder and connected therewith by a separating port; elecertically operated valve means for closing said separating port as said piston approaches its end of said cylinder, so as to isolate the air compressed in said jet-combustion chamber from the air compressed in the end of said cylinder; electrically-open atcd means for substantially simultaneously injecting fuel into the compressed air in said jet-combustion chamber and into the compressed air in said cylinder; electrically operated means for substantially simultaneously exploding the two said injections of fuel; at least one nozzle exhaust port leading from each said jet combustion chamber; electrically operated nozzle valve means for closing said nozzle exhaust port while air is port to permit the passage of expanded gases, said separating port remaining closed during the expansion and explosion process, the expanded gases from the jet-combustion chamber being used to supply external power while the expanded gases in the cylinder are used to drive the piston toward the other end of said cylinder, where a similar explosion takes place.

4. An engine of the type described, having its own means for compressing air and including in combination at least one compressor cylinder; piston means reciprocatable therein; at least one generally enclosed chamber means adjacent said cylinder and connected therewith only by a port; valve means actuated by said piston means for closing said port as said piston approaches said port, so as to completely isolate the air compressed thereby in said enclosed chamber from the portion of the air compressed in said cylinder; means for injecting fuel into the compressed air in said cylinder; means for exploding the said injection of fuel, the volume of said chamber and the volume of said cylinder during explosion of said fuel being so related that while the gases from said enclosed chamber are used to supply external power, the expanded gases in the cylinder are used to drive the piston in the opposite direction until a similar explosion again supplies power for driving said piston, said cylinder gases doing no external work; an electric circuit controlling the operation of said valve means, fuel injector. and fuel exploding means; switch means in said circuit actuated by said piston means; and relays in said circuit actuated by said switch means and adapted to time the operation of said valve means, injector and exploding means.

5. An engine of the type described, having its own means for compressing air and including in combination at least one compressor cylinder provided with a closed chamber adjacent each end; piston means reciprocatablc therein to alternately compress air toward each of the two ends of said cylinder; at least one generally enclosed chamber means adjacent said cylinder and connected therewith only by a port; valve means actuated by said piston means for closing said port as said piston approaches said port, so as to completely isolate the air in said enclosed chamber from the portion of the air compressed in said cylinder; means for injecting fuel into the compressed air in said cylinder; and means for exploding the said injection of fuel, the volume of said chamber and the volume of said cylinder during explosion of said fuel being so related that while the gases from said enclosed chamber are used to supply external power, the expanded gases in the cylinder are used to drive the piston in the opposite direction until a similar explosion again supplies power for driving said piston, said cylinder gases doing no external work and whereby the explosion at on: end of the cylinder drives the piston to compress toward the other end and vice versa.

References Cited in the file of this patent UNITED STATES PATENTS 2,200,892 Pescara May 14, 1940 10 Renick Feb. 18, 1941 Steiner June 24, 1941 Iohansson Nov. 25, 1947 Welsh Apr. 19, 1949 Mallory June 20, 1950 FOREIGN PATENTS Great Britain Dec. 9, 1947 

